Optical recording medium having pit rows on every other boundary and reproducing method thereof

- Sharp Kabushiki Kaisha

Grooves and lands are provided to a magneto-optical disk so as to be alternately arranged, and recording bit strings are formed on the grooves and lands respectively so that information is recorded. Moreover, pit rows are formed on boundary sections between the adjoining grooves and lands so that address information of a recording/reproducing track is recorded, and the pit rows are formed every other boundary section. When the grooves and the lands are scanned as the recording/reproducing track by a light, an address of the recording/reproducing track is read out from the pit rows, and successively, discrimination is made whether the recording/reproducing track which is scanned by an optical spot is the groove or the land. This prevents crosstalk which causes inclusion of address information in the next pit rows, thereby, making it possible to obtain accurate address information. Moreover, since a total number of formed pit rows can be decreased and accuracy in a shape of pits is relieved, an optical recording medium can be easily produced.

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Claims

1. An optical recording medium comprising:

grooves and lands, said grooves and lands being alternately provided, recording bit strings being formed on said grooves and lands respectively; and
pit rows representing address information of a recording/reproducing track, said pit rows being formed on every other boundary by digging boundaries between said adjoining grooves and lands.

2. The optical recording medium as defined in claim 1, wherein either of said groove or land includes a mark section with refractive index of a light which is different from refractive index of each groove and land, discrimination being made whether the recording/reproducing track which is scanned by a light is a groove or a land based upon detection of said mark section.

3. The optical recording medium as defined in claim 2, wherein said mark section is a pit which has been locally formed in a vicinity of a center of either of each groove or land.

4. The optical recording medium as defined in claim 2, wherein said mark section is a pit which has been locally and linearly formed in a vicinity of a center of either of each groove or land.

5. The optical recording medium as defined in claim 3, wherein said mark section has a depth of approximately.lambda./(4n) and a width of 0.3 T to 0.4 T where n is refractive index of a substrate of said optical recording medium, T is a track pitch of the recording/reproducing track, and.lambda. is a wavelength of a light to be emitted on the recording/reproducing track.

6. The optical recording medium as defined in claim 1, further comprising a substrate, said optical recording medium satisfies the following relationships:

7. The optical recording medium as defined in claim 1, further comprising a substrate, said optical recording medium satisfies the following relationships:

8. The optical recording medium as defined in claim 1, wherein said grooves and lands where pits included in said pit rows have been formed so as to have different depths.

9. The optical recording medium as defined in claim 1, wherein said pit rows include pits, the pits having depth which is same as the depths of said grooves.

10. The optical recording medium as defined in claim 9, wherein said grooves and lands are formed respectively in a continuous form.

11. The optical recording medium as defined in claim 1, wherein the pits included in said pit rows are formed more deeply than said grooves.

12. A reproducing method for an optical recording medium, the optical recording medium comprising, (1) grooves and lands which are alternately arranged and (2) pit rows which are formed on every other boundary by digging boundaries between said adjoining grooves and land so that address information of a recording/reproducing track is recorded, said method comprising:

the first step of when said grooves or lands as the recording/reproducing track in said optical recording medium is scanned by a light in a direction of the track, reading out an address of the recording/reproducing track from said pit rows;
the second step of discriminating whether the recording/reproducing track which is scanned by the light is said groove or land; and
wherein said address of the recording/reproducing track are recorded by said pit rows so that its value increases or decreases by two at a time,
either of said grooves or lands where said pit rows have been formed on said boundary sections between said grooves and lands are managed by an address which is same as of said recording/reproducing track, the other address of either of said grooves or lands is specified by adding and subtracting one to or from the address of the recording/reproducing track.

13. The reproducing method as defined in claim 12, wherein said second step includes the step of when said grooves and lands as the recording/reproducing track of said optical recording medium is scanned by the light in the direction of the track, discriminating whether the recording/reproducing track which is scanned by the light is said groove or land by detecting polarity of a tracking signal.

14. The reproducing method as defined in claim 12, wherein:

said address of the recording/reproducing track is recorded by said pit rows so that its value successively increases or decreases by one at a time,
said grooves and lands where the pit rows have been formed on said boundary sections between said grooves and lands are managed by a same address.

15. A reproducing method for an optical recording medium, the optical recording medium comprising, (1) grooves and lands which are alternately arranged and (2) pit rows which are formed on every other boundary by digging boundaries between said adjoining grooves and lands so that address information of a recording/reproducing track is recorded, said method comprising:

the first step of when said grooves or lands as the recording/reproducing track in said optical recording medium is scanned by a light in a direction of the track, reading out an address of the recording/reproducing track from said pit rows;
the second step of discriminating whether the recording/reproducing track which is scanned by the light is said groove or land; and wherein:
said address of the recording/reproducing track is recorded by said pit rows so that its value increases or decreases by one at a time,
either of said grooves and lands where said pit rows have been formed on said boundary sections of said grooves and lands is managed by an address which is same as of the recording/reproducing track, the other address of either of said grooves or lands being converted according to the formula: (address by pit rows)+(a total number of tracks)/2 so as to be specified.

16. A reproducing method for an optical recording medium, the optical recording medium comprising, (1) grooves and lands which are alternately arranged and (2) pit rows which are formed on every other boundary by digging boundaries between said adjoining grooves and lands, so that address information of a recording/reproducing track is recorded, said method comprising:

the first step of when said grooves or lands as the recording/reproducing track in said optical recording medium is scanned by a light in a direction of the track, reading out an address of the recording/reproducing track from said pit rows;
the second step of discriminating whether the recording/reproducing track which is scanned by the light is said groove or land; and wherein:
said address of the recording/reproducing track is recorded by said pit rows so that its successively value increases or decreases by one at a time,
either of said grooves or lands where said pit rows have been formed on said boundary sections of said grooves and lands is managed by an address which is same as of the recording/reproducing track, the other address of either of said grooves or lands being converted according to the formula: (a total number of tracks)-(address by pit rows)+1 so as to be specified.
Referenced Cited
U.S. Patent Documents
5448552 September 5, 1995 Onagi
5493561 February 20, 1996 Nishiuchi et al.
Foreign Patent Documents
3714804 A1 November 1988 DEX
4212663 A1 January 1993 DEX
58-23333 February 1983 JPX
63-57859 November 1988 JPX
2-156423 June 1990 JPX
5-81717 April 1993 JPX
Other references
  • "Improvement of Track Density by Land and Groove Recording on Phase Change Optical Disk," N. Miyagawa et al., Conference Digest, Joint International Symposium on Optical Memory and Optical Data Storage, 1993, pp. 57-58. "Suppression of Crosstalk by Control of Groove Depth in Recording on Land and Groove," N. Miyagawa et al., Abstracts of the 53rd Lecture Meeting held by Applied Physics Association, No. 3, 18a-T-3, 1992, p. 948. "Super Resolution in Magneto-Optical Disks," M. Kaneko et al., Journal of Applied Magnetics Institute, vol. 15, No. 5, 1991, pp. 838-844.
Patent History
Patent number: 5673250
Type: Grant
Filed: Jun 6, 1995
Date of Patent: Sep 30, 1997
Assignee: Sharp Kabushiki Kaisha (Osaka)
Inventors: Michinobu Mieda (Shiki-gun), Junji Hirokane (Nara), Akira Takahashi (Nara), Kenji Ohta (Kitakatsuragi-gun), Shigeo Terashima (Tenri)
Primary Examiner: Muhammad N. Edun
Attorneys: David G. Conlin, William J. Daley, Jr., Brian L. Michaelis
Application Number: 8/468,776
Classifications
Current U.S. Class: 369/2754; Special Groove (e.g., Particular Groove Shape) (369/277); Radiation Beam Modification Of Or By Storage Medium (369/100); 369/58; 369/32
International Classification: G11B 700;